Rotary pump



June 1, 1965 H. TISSOT ROTARY PUMP Filed Feb. 4, 1965 United States Patent f ROTARY PUMl Hans Tissot, Gmundnerstrasse 6, Vocklabruck, Austria Filed Feb. 4, 1963, der. No. 255,830 7 Claims. ((Il. 103-135) This invention relates to a rotary pump which comprises a rotor eccentrically mounted in a housing and formed with suitable openings, in which sealing members are inwardly and outwardly slidably mounted, which consist of three-sided prisms and have a curved outside peripheral surface guided on the cylindrical inside wall of the housing opening.

In known rotary pumps of this type, the sealing members have'in cross-section the shape of an isoscelestriangle, the base of which ismuch shorter than the two sides and forms the curved peripheral surface. These sealing members are inserted in wedge-shaped openings of the rotor, which are symmetrical with respect to radial planes of the rotor and consequently to the altitude on the base, of the triangle and the spacing of which is large compared to the width of their base. Compared to other rotary pumps, such rotary pumps have the essential advantage that the curved peripheral surface of the sealing members is maintained in engagement with the wall of the housing opening by centrifugal force duringthe rotation of the rotor so that the springs otherwise frequently required with rotary pumps and serving for urging the sealing mem-. bers outwardly can be eliminated and the rotor and generally the entire pump is simple in construction. On the other hand, the rotary pump thus described has the disadvantage that the sealing members have a relatively small mass so that they are urged with sufficient pressure against the wall of the housing opening only at very high speeds. Besides, when contaminated liquids are being handled there is a danger that grains of sand contained in the liquid may form scratches in the curved peripheral surfaces of the sealing members so that the efficiency of the pump is reduced. Besides, these pumps do not ensure that the trailing peripheral surface portions of the sealing members will be urged under sufficient pressure against the complementary surfaces of the openings in the rotor so that a leakage of liquid may occur at these points. In hard usage, there is an additional danger that foreign matter may deposit in the gap defined between the leading face of a sealing member in extended position and the complementary surface of the opening of the rotor; owing to the great taper of the wedge-shaped openings and of the sealing members, such foreign matter can no longer be flushed out by the liquid so that the retracting movement of the sealing members may result in damage to the sealing members and to the rotor and, in the case of larger deposits of foreign matter, even in damage to the hous ing by the scaling members, when the same can no longer be fully retracted. It is apparent from the above that the known pumps of this type are suitable only for handling clean liquids. Besides, these pumps cannot be sealed sufliciently to be self-priming.

In addition to the above-mentioned rotary pumps having sealing members which are extended by springs and consist suitably of slide members or rollers and have the same disadvantages as the pump described regarding sealing effect and the liability to be deranged in hard usage, other rotary pumps have been disclosed which are similar in operation to the pump described first hereinbefore and in which the sealing members have also a curved peripheral surface held in engagement with the complementary housing bore only by centrifugal force. Such pumps have sealing members of, e.g., L- or T-shaped cross-section, one flange of the L-section or the web of the T-section being guided in radial openings of the rotor, so

3,185,348 Patented June 1, 1965 that the correspondingly curved outer portion of the section engages the periphery of the housing opening over a large area. These sealing members too have only a small mass so that an adequate seal between the sealing member and the opening wall cannot be achieved in spite of the engagement over a large area. Besides, the sealing members are thin-walled so that they tend to be deformed in hard usage and particularly when foreign matter has entered between the periphery of the rotor and the protruding portions of the sealing members. To give the sealing members a certain freedom of movement, the openings in the rot-or have an outward taper, which involves an extremely complicated manufacture of the rotor.

All disadvantages set forth are eliminated by the invention. The same relates to a rotary pump of the type mentioned first hereinbe'fore and resides essentially in that the sealing members have substantially the shape of a right-angled triangle in cross-section, one of the short side faces being curved and cooperating with the inside wall of the housing, the other short side face constituting the trailing face of the sealing member and cooperating with the motion-transmitting leading face of the rotor, and the width of the curved short side face being of an order of magnitude of at least one third to two thirds of the peripheral spacing of corresponding portions on adjacent sealing members. The design according to the invention results in sealing members having a relatively large mass so that they are forced under relatively high pressure against the inside wall of the housing opening under the action of centrifugal force. Owing to the engagement over a large area, the sealing effect cannot be substantially impaired by any scratches on the curved surfaces. More particularly, the sealing members constitute inherently rigid parts, which are hardly subject to Wear and cannot set up resonant vibration. The resulting radial arrangement of the trailing short side face, which cooperates with a complementary radial backing surface of the opening of the rotor, ensures a reliable drive of the sealing members by the rotor without canting. In addition, the sealing members are urged under high pressure against the radially extending surfaces of the openings of the rotor so that a good seal is ensured also in this area.

In an embodiment of the invention, the identical sealing members have the shape of an unequal-sided triangle and with their shortest side face bear on the substantially radial guide faces at the rear of the angle-shaped openings of the rotor. This results in the formation of an acuteangled edge between the hypotenuse face and the curved short side face, which edge has a scraping action and causes the liquid to flow inwardly from the cylindrical periphery, against which it is urged by centrifugal force. It may be mentioned that the largest angle of the sealing members, namely, the angle between the two short sides, may be at least or up to To increase the sealing action of the sealing members and the pressure by which they are urged against the housing, it is a development of the invention to provide the rotor with trailing faces which coact with the hypotenuse faces of the sealing members and which are formed with a recess extending as far as to the periphery of the rotor, through which recess the liquid retained in front of the sealing member is admitted to the hypotenuse face. The force acting on each sealing member as a result of this admission is resolved into two components, one of which urges the curved sealing face against the housing whereas the other urges the trailing guide face of the sealing member against the corresponding leading guide face of the rotor. During the retracting movement of the sealing members in operation, any foreign matter can escape through these recesses so that the guide faces for the sealing member cannot be contaminated to a disturbing degree even when highly contaminated liquids are being handled.

effect, the pump according to the invention is self-priming and may be used for handling liquid and gaseous fluids. In the accompanying drawing, the invention is shown by way of example. .FIGS. 1 and 2, respectively, show a pump in front and side elevations, partly in section.

- The pump has a housing 3 which is closed at both ends by end covers 1, 2 and which confines a cylindrical interior space 4, in which a rotor 5 is keyed to a shaft 6 mounted in the cover 2, which is designed as a bearing cover. With respect to the cylindrical interior space 4-,

the rotor is eccentric and has angle-shaped openings 7, in

which prismatic sealing members 8 are disposed, which have the shape of substantially right-angled triangles in cross-section. One short side face of these sealing memhers is curved in conformity with the cylindrical shape of the wall of the interior space and the other short side face ltl extends substantially radially and constitutes the trailing face of the sealing members 8. The hyoptenuse face 11 includes with the curved short side face h an acuteangled scraper edge 12.

The housing 3 accommodates an inlet opening 13 and an outlet opening 14,.which may be connected by tubular fittings 15, 16 to hose conduits, pipes or the like. The inlet openingl? is spaced farther from the point 17 of least spacing between rotor and housing than the outlet opening 14. As a result, the spaces 1% enclosed between two successive sealing members 8, the housing and the rotor are larger adjacent to the suction opening 13 than adjacent to the outlet opening 14. In addition, thetrailing faces 19 of the rotor 5, which face the hyptotenuse faces 11, are formed with inwardly tapered semi-circular grooves 20.

During operation, the tubular fitting 15 of the pump is connected to a' suction conduit, the tubular fitting 16 is connected to a discharge conduit and the shaft 6 is driven I in the direction of the arrow 21; the shaft 6 may be connected, e.g., to an electric motor, an internal-combustion engine or the power take-off of a tractor or the like. The sealing members 8 may be made from a material of low friction, such as metal, plastic or ebonite, and their faces 9 are urged by centrifugal force against the cylindrical walls. Because the spaces 18 are increased in size when the sealing rnembers have passed the point 17 and during the movement past the opening 13, a suction is obtained so that a subatmospheric pressure is produced in the suction conduit and finally causes the liquid to be sucked. Adjacent to the opening 13 the liquid is then received and handled by the spaces 18. Owing to the decrease in the size of the spaces 18 towards the opening 14-, pressure is built up in the liquid and acts on the hypotenuse face 11 of the sealing members to cause the short side faces L14), 9 of these sealing members to be urged against the leading faces 22 .of the rotor and the inside wall of the housing until the liquid emerges under pressure through the opening 14. 7

What is claimed is: 1. A rotary pump comprising, in combination: (a) a housing having a substantially cylindrical internal Wall; (b) a rotor mounted in said housing for rotation about an axis, said axis being eccentric with respect to said wall,

(1) said rotor being formed with a plurality of circumferentially spaced radial recesses and having a leading face and a trailing face in each recess when said rotor rotates in a predetermined direction;

(c) drive means for rotating said rotor in said direction; and

(d) a plurality of circumferentially spaced sealing members at least partly received in respective recesses of said rotor,

(1) each sealing member having the approximate sectional shape of a righ -angled triangle in a radial plane and correspondingly having three axially extending faces,

(2) the first of said faces conformingly and slidably engaging aid wall,

(3) the second face being arranged opposite said trailing face and abuttingly engaging the same during said rotation of the rotor, and

(4) the third face connecting said first and second faces and being arranged opposite said trailing face,

(5) said first face corresponding to a third ide of said triangle which issho-rter than the ide corresponding to said third face and longer than the side corresponding to the second face.

2. A pump as set forth in claim 1, wherein the circumferential length of said first face is between one third and two thirds of the circumferential spacing of corresponding portions of said first face and of the first face of a circumferentially successive sealing member.

3. A rotary pump as set forth in claim 1, in which each of said trailing faces is formed with asecondary recess having an open end at the periphery of said rotor between two of said first mentioned recesses and an open side in said trailing facef 4. A rotary pump as set forth in claim 3, in which said secondary recess has a semicircular cross-section in an axial plane and tapers from said open end in a radially inward direction.

5. A rotary pump as set forth in claim 1, in which said first and second faces of each sealing member include an angle of l00 degrees.

6. A rotary pump as set forth in claim 1, in which said pump housing is formed with an inlet opening and an outlet opening angularly spaced in opposite directions from that circumferential portion of said wall which is closest to the axis of said rotor, the angular spacing of aid inlet opening from said wall portion being greater than the angular spacing of said wall portion from said outlet opening.

7. A sealing member fora rotary pump, said sealing member extending in a predetermined direction and having the approximate cross-sectional hape of a right-angled triangle in a plane perpendicular to said direction, the sides of said triangle corresponding to respective three faces of said sealing member extending in said direction, the first of said faces being a convex segment of a cylinder about an axis extending in said direction, the second face extending substantially at right angles from said first face, and the third face connecting said first and second faces, the side of said triangle corresponding to said first face being longer than the side of the triangle corresponding to said second face and shorter than the side corresponding to said third face.

References Cited by the Examiner UNITED STATES PATENTS 1,651,336 11/27 WiSSlfii 103136 2,521,236 9/50 MacPherson 103-164 2,628,563 2/53 Rhine 103-136 2,636,667 4/53 Frei 230l52 2,830,543 4/58" Rotlh 103135 2,856,860 '10/58 Roth 103l35 KARL J'. ALBRecnr, Primary Examiner.

JOSEPH H. BRANSON, JIL, Examiner. 

1. A ROTARY PUMP COMPRISING, IN COMBINATION: (A) A HOUSING HAVING A SUBSTANTIALLY CYLINDRICAL INTERNAL WALL; (B) A ROTOR MOUNTED IN SAID HOUSING FOR ROTATION ABOUT AN AXIS, SAID AXIS BEING ECCENTRIC WITH RESPECT TO SAID WALL, (1) SAID ROTOR BEING FORMED WITH A PLURALITY OF CIRCUMFERENTIALLY SPACED RADIAL RECESSES AND HAVING A LEADING FACE AND A TRAILING FACE IN EACH RECESS WHEN SAID ROTOR ROTATES IN A PREDETERMINED DIRECTION; (C) DRIVE MEANS FOR ROTATING SAID ROTOR IN SAID DIRECTION; AND (D) A PLURALITY OF CIRCUMFERENTIALLY SPACED SEALING MEMBERS AT LEAST PARTLY RECEIVED IN RESPECTIVE RECESSES OF SAID ROTOR, (1) EACH SEALING MEMBER HAVING THE APPROXIMATE SECTIONAL SHAPE OF A RIGHT-ANGLED TRIANGLE IN A RADIAL PLANE AND CORRESPONDING HAVING THREE AXIALLY EXTENDING FACES, (2) THE FIRST OF SAID FACES CONFORMINGLY AND SLIDABLY ENGAGING SAID WALL, (3) THE SECOND FACE BEING ARRANGED OPPOSITE SAID TRAILING FACE AND ABUTTINGLY ENGAGING THE SAME DURING SAID ROTATION OF THE ROTOR, AND (4) THE THIRD FACE CONNECTING SAID FIRST AND SECOND FACES AND BEING ARRANGAED OPPOSITE SAID TRAILING FACE, (5) SAID FIRST FACE CORRESPONDING TO THE THIRD SIDE OF SAID TRIANGLE WHICH IS SHORTER THAN THE SIDE CORRESPONDING TO SAID THIRD FACE AND LONGER THAN THE SIDE CORRESPONDING TO THE SECOND FACE. 